/*
 * $Id$
 * This file is a part of the Arakhne Foundation Classes, http://www.arakhne.org/afc
 *
 * Copyright (c) 2000-2012 Stephane GALLAND.
 * Copyright (c) 2005-10, Multiagent Team, Laboratoire Systemes et Transports,
 *                        Universite de Technologie de Belfort-Montbeliard.
 * Copyright (c) 2013-2016 The original authors, and other authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.arakhne.afc.vmutil;

import java.io.InputStream;
import java.net.URL;

import org.eclipse.xtext.xbase.lib.Pure;

/**
 * This interface provides the standard JRE implementation to load resources according to
 * several heuristics:<ul>
 * <li>search the resource in class paths;</li>
 * <li>search the resource in ./resources subdirectory in class paths.</li>
 * </ul>
 *
 * @author $Author: sgalland$
 * @version $FullVersion$
 * @mavengroupid $GroupId$
 * @mavenartifactid $ArtifactId$
 * @since 7.0
 */
class StandardJREResourceWrapper implements ResourceWrapper {

	/** Prefix (or directory name) where resources may be located.
	 */
	public static final String RESOURCE_PREFIX = "resources/"; //$NON-NLS-1$

	/** Construct a wrapper.
	 */
	StandardJREResourceWrapper() {
		//
	}

	@Override
	@Pure
	public URL getResource(ClassLoader classLoader, String path) {
		if (path == null) {
			return null;
		}
		String resourcePath = path;
		if (path.startsWith("/")) { //$NON-NLS-1$
			resourcePath = path.substring(1);
		}

		final ClassLoader loader = (classLoader == null)
				? ClassLoaderFinder.findClassLoader()
				: classLoader;
		assert loader != null;

		URL url = loader.getResource(resourcePath);

		if (url == null) {
			// Try to find in ./resources sub directory
			url = loader.getResource(RESOURCE_PREFIX + resourcePath);
		}
		return url;
	}

	@SuppressWarnings("resource")
	@Override
	@Pure
	public InputStream getResourceAsStream(ClassLoader classLoader, String path) {
		if (path == null) {
			return null;
		}
		String resourcePath = path;
		if (path.startsWith("/")) { //$NON-NLS-1$
			resourcePath = path.substring(1);
		}
		ClassLoader loader = classLoader;
		if (loader == null) {
			loader = ClassLoaderFinder.findClassLoader();
		}
		if (loader == null) {
			loader = Resources.class.getClassLoader();
		}

		assert loader != null;
		InputStream is = loader.getResourceAsStream(resourcePath);
		if (is == null) {
			// Try to find in ./resources sub directory
			is = loader.getResourceAsStream(RESOURCE_PREFIX + resourcePath);
		}
		return is;
	}

	@Override
	@Pure
	public String translateResourceName(String resourceName) {
		return resourceName;
	}

}